Value-Added Products From FGD Sulfite-Rich Scrubber Materials

Abstract

Massive quantities of sulfite-rich flue gas desulfurization (FGD) scrubber materials are produced every year in the USA. In fact, at present, the production of wet sulfite-rich scrubber cake outstrips the production of wet sulfate-rich scrubber cake by about 6 million tons per year. However, most of the utilization focus has centered on FGD gypsum. Therefore, we have recently initiated research on developing new strategies for the economical, but environmentallysound, utilization of sulfite-rich scrubber material.In this exploratory project (Phase I), we attempted to ascertain whether it is feasible to develop reconstituted wood replacement products from sulfite-rich scrubber material. In pursuit of this goal, we characterized two different wet sulfite-rich scrubber materials, obtained from two power plants burning Midwestern coal, for their suitability for the development of value-added products. The overall strategy adopted was to fabricate composites where the largest ingredient was scrubber material with additional crop materials as additives. Our results suggested that it may be feasible to develop composites with flexural strength as high as 40 MPa (5800 psi) without the addition of external polymers. We also attempted to develop load-bearing composites from scrubber material, natural fibers, and phenolic polymer. The polymer-to-solid ratio was limited to ≤ 0.4. The formulated composites showed flexural strengths as high as 73 MPa (10,585 psi). We plan to harness the research outcomes from Phase I to develop parameters required to upscale our value-added products in Phase II. Abstract------------------------------------------------------------------------------3 Executive Summary---------------------------------------------------------- 4 TABLE OF CONTENTS Page Disclaimer--------------------------------------------------------------------------2 Results and Discussion---------------------------------------------------10 Chemical analysis of scrubber materials---------------------------10 Thermal analysis of scrubber materials----------------------------11 Vibrational spectra of scrubber materials--------------------------12 Effects of natural fibrous material on composites--------------14 Effects of natural polymer and proteins---------------------------16 Effects of formation temperature and pressure-----------------24 Load bearing materials------------------------------------------------25 Summary and Conclusions--------------------------------------------30 References-------------------------------------------------------------------32 5 EXECUTIVE SUMMARYIn our pursuit to develop value-added wood substitute products from sulfite-rich FGD scrubber material, we collected samples of scrubber material from two different power plants. These power plants burned high-sulfur Midwestern bituminous coal and were fitted with wet FGD scrubbers. The scrubber samples had not undergone stabilization with fly ash and were in a wet cake form. The as-received, but air-dried, scrubber materials were subjected to c...